The present invention relates to detergent compositions suitable for topical application for cleansing the human body, such as the skin and hair. In particular, it relates to self foaming gel compositions, conveniently propellant driven and of the xe2x80x9cbag-in-canxe2x80x9d variety, which are suitable for use as cleansing compositions, and in particular for use as shower gels, which are formulated to give mild cleansing and optionally conditioning of the skin, and which are dispensed as a gel but generate a foam which is rich and feels luxurious to use.
Self foaming gel compositions formulated to cleanse the skin are well known. Such products may be considered superior to mousse type cleaning products, which suffer from the disadvantage that when applying a pre-formed mousse onto the skin, the mousse tends to break down and dissipate quickly, without providing substantive lather. In contrast, self-foaming compositions are dispensed initially as viscous liquids or gels, which generate copious amounts of lather as they are spread over the skin and optionally rubbed.
It is also known to formulate products which provide in particular a cleansing benefit, which are in the form of a bag in can gel composition. For example, WO 97/03646 discloses a bag in can cleansing composition which contains a base composition which has a viscosity of at least 9,500 cps, which in practice is achieved by the use of a specified thickener. The composition is said to have superior properties by virtue of the relatively high viscosity, in terms of improved stability and the ability to incorporate higher levels of volatile self foaming agent.
A variety of problems have been found to be associated with such bag in can gel compositions. A particular problem relates to the manufacture of such compositions, and especially how to dose into a bag in can arrangement a gel composition which is not so viscous so as to cause problems in the dosing of that composition, and/or to require the use of specialist equipment to dose the composition. In particular, it is clear from the teaching of WO97/03646 that the composition is required to have a minimum viscosity of 9,500 cps. As such, the composition is difficult to process and dose on conventional filling lines.
An associated problem is that in preparing surfactant based gel compositions which subsequently have a self foaming volatile component (such as a liquifiable propellant gas) dosed into them, a number of these compositions experience a drop in viscosity when the self foaming volatile component is dosed into them. This can be disadvantageous, since it is desirable that the product as dispensed has a good, relatively viscous gel structure. This in turn is so that the dispensed product will not only have good manipulation properties for the user, but also so that the relatively rigid gel structure is able to accommodate a relatively high amount of self foaming agent (e.g. liquifiable propellant gas), and to entrap it relatively well. This is so that the resulting product foams well when lathered (by virtue of the relatively high content of volatile component), but also so that it does not foam prematurely after being dispensed.
It is thought that because of the phenomena described of thinning when the propellant gas is dosed that it is necessary for the base composition to have a relatively high initial viscosity, such that any thinning of the product when propellant gas is dosed which does occur is not too deleterious to the properties of the final product as dispensed.
GB-A-2,213,160 describes a soap free post foaming gel composition comprising a major amount of water, 3-23% of a water soluble anionic alkali metal alkyl ether sulphate surfactant, 1-24% of dispersible nonionic ethoxylated fatty alcohol or fatty ester, and 5-20% saturated aliphatic hydrocarbon foaming agent, with the anionic surfactant and the ethoxylated fatty alcohol or ester being present in pre-determined ratios. Compositions according to this teaching are based on the specific combination of the anionic and nonionic surfactants, i.e. the alkyl ether sulphate and the nonionic ethoxylated fatty alcohol or fatty ester, and the criticality of each ingredient in the composition is clearly referred to.
A further problem which may be encountered relates to the stability of such cleansing compositions, especially those compositions which are based on non-soap surfactants. Regarding scap-based compositions, post foaming shaving gels employing soap based formulations are well known in the art. However, fundamentally it is desirable to create a cleansing composition based on non-soap surfactants, since by eliminating or reducing any soap to a low level the mildness of the composition may be improved. However, the inclusion of only a low level of soap means that it can be relatively difficult to structure and stabilise the cleansing composition.
We have found a way of formulating such self foaming gel or viscous liquid compositions such that they can deliver effective cleansing and optionally conditioning of the skin, are relatively easy to manufacture, and also have the desired stability and structure characteristics.
Thus, according to a first aspect of the invention, there is provided a packaged aqueous self foaming liquid cleansing composition comprising a base composition comprising a surfactant selected from anionic, nonionic, amphoteric, zwitterionic or cationic surfactants, and mixtures thereof, a hydrophobic component, and a post foaming agent, wherein the composition is substantially free of soap and thickens on the addition of the post foaming agent to the base composition.
Compositions according to the invention may conveniently be packaged in a so-called bag in can package, in which the cleansing composition is packaged inside a flexible bag, which is itself disposed in a can, with a suitable propellant gas located between the can and bag which pressurises the composition in the bag to a degree where it can be dispersed from suitable hardware.
Alternatively, the composition can be packaged in a pressurised bladder type package, in which the composition is packaged in what amounts to an elasticated bladder, which bladder maintains the contents of the bladder under positive pressure. This pressure is sufficient to cause the contents of the bladder to be dispensed via a closure mechanism located in the package.
In a highly preferred embodiment of the invention, the aqueous composition, shortly prior to being mixed with the self foaming agent, and subsequently being dosed into the product package, has a viscosity of less than 9,000 mPa.s, preferably less than 8,000 mPa.s, more preferably less than 5,000 mPa.s, and even more preferably less than 3,000 mPa.s. It is also highly preferred that packaged composition is prepared by preparing the aqueous base portion of the composition as a somewhat viscous liquid, but excluding the post foaming agent. Just prior (say within 1 minute, preferably with in 10 seconds, preferably within 1 second) to dosing the aqeuous composition into the package of the arrangement (which in the case of a bag in can package is conveniently already located within the can), the post foaming agent is dosed into the aqueous composition, which is then rapidly dosed into a suitable container, such as e.g. a bag within the dispensing package.
However, compositions according to the invention typically thicken on the addition of self foaming agent to form a viscous gel, such that the dispensed composition has good handling and sensory properties, and also such that it retains the post foaming agent well after being dispensed.
By manufacturing the composition in this manner, it is possible to make the aqueous base such that it has a relatively low viscosity, and is therefore easy to process. However, introduction of the post foaming agent into the composition just prior to dosing the composition into the container ensures that any thickening of the composition, which is desirable bearing in mind that the form of the dispensed composition is as a viscous liquid or gel, does not occur until the composition is inside the container. This method therefore simplifies the manufacturing process. Gel compositions according to the invention are not simple propellant driven compositions, and may not be dispensed from conventional propellant driven aerosol packaging, since they are too viscous to dispense from such conventional single compartment propellant driven aerosal packaging. It is also important that the packaged composition does not have any headspace, since if this were to occur it could cause the composition to be dispensed as a mousse.
Where the packaged composition utilises bag in can packaging, compositions according to the invention have two associated gases; a propellant gas and a post (self) foaming agent. The propellant gas is that which is contained within the can, but acts against the outside of the bag in which the composition is contained to dispense the composition when an actuator on the can is used. The propellant gas can be any suitable gas, but is conveniently a non-liquifiable propellant gas, such as compressed air, though any propellant which would function to dispense the composition would be suitable. The propellant gas is present in the packaged composition at any required and suitable level, but is typically present in the packaged product at levels sufficient to produce a satisfactory dispensing pressure, which will typically be 2-12 bar, more preferably 3-9 bar.
The other component required in such packaged composition according to the invention is a post foaming agent. The post foaming agent is present in compositions according to the invention to allow the composition, which is dispensed in the form of a stable gel, once dispensed to generate a foam, as it evaporates on contact with a skin surface, thereby experiencing body heat. The generation of a foam provides a product which has various desirable consumer attributes, including ease of handling and spreading, and desirable sensory properties.
Suitable post foaming agents for inclusion in compositions according to the invention are volatile or liquifiable, and include (but are not limited to) hydrocarbons, such as isobutane and isopentane. Post foaming agents are present in packaged compositions according to the invention at levels of 4-15%, more preferably 5-10% by weight of the packaged composition. Suitable post foaming agents should be capable of being contained in compositions according to the invention as liquids, which may have been formed under the pressure to which the packaged composition has been subjected. As such, it is also desirable and may even be essential that packages in which the packaged composition is stored have no head space, to prevent the premature evaporation of the post foaming agent.
Packaged compositions according to the invention contain a blend of hydrophobic components, including perfume oils and hydrophobic benefit agent components, and hydrocarbon post foaming agents, which are blended and matched, and chosen in conjunction with a suitable surfactant or blend of surfactants, in order to form a stable isotropic system. Compositions according to the invention are often microemulsions.
The hydrophobic component in the composition may conveniently be a benefit agent, a perfume oil, or another hydrophobic component. The composition according to the invention may conveniently be suitable for cleansing, and in addition optionally moisturising, conditioning or protecting the skin. Where the hydrophobic component in the composition is a benefit agent, this may be included in the composition to moisturise, condition and/or protect the skin. By xe2x80x9cbenefit agentxe2x80x9d is meant a substance that softens the skin (stratum corneum) and keeps it soft by retarding the decrease of its water content, and/or protects the skin. However, substantial deposition on the skin of a hydrophobic component or benefit agent is not necessarily a feature of compositions according to the invention.
Preferred hydrophobic components which may be solid or liquid at room temperature, but in compositions according to the invention are to be found in liquid form (either by virtue of being liquid at room temperature themselves, or by being solubilised in a hydrophobic liquid component so as to provide a liquid composition) include:
a) silicone oils, gums and modifications thereof such as linear and cyclic polydimethylsiloxanes, amino, alkyl alkylaryl and aryl silicone oils;
b) fats and oils including natural fats and oils such as jojoba, soyabean, rice bran, avocado, almod, olive, sesame, persic, castor, coconut, milk oils; cacaco fat, beef tallow, lard; hardened oils obtained by hydrogenating the aforementioned oils; and synthetic mono, di and triglycerides such as myristic acid glyceride and 2-ethylhexanoic acid glyceride;
c) waxes such as carnauba, spermaceti, beeswax, lanolin and derivatives thereof;
d) hydrophobic plant extracts;
e) hydrocarbons such as liquid paraffins, petroleum jelly, microcrystalline wax, ceresin, squalene, squalane, and mineral oil;
f) higher fatty acids such as lauric, myristic, palmitic, stearic, behenic, oleic, linoleic linolenic, lanolic, isostearic and poly unsaturated fatty acids (PUFA) acids;
g) higher alcohols such as lauryl, cetyl, steryl, oleyl, behenyl, and 2-hexadecanol alcohol;
h) esters such as cetyl octanoate, myristyl lactate, cetyl lactate, isopropyl myristate, myristyl myristate, isopropyl palmitate, isopropyl adipate, butyl stearate, decyl oleate, cholesterol isostearate, glycerol monostearate, glycerol distearate, glycerol tristearate, alkyl lactate for example lauryl lactate, alkyl citrate and alkyl tartrate;
i) essential oils such as fish oils, mentha, jasmine, camphor,white cedar, bitter orange peel, ryu,turpentine, cinnamon, bergamont, citurs unshiu, calamus, pine, lavender, bay, clove, hiba, eucalyptus, lemon, starflower, thyme, peppermint, rose, sage, menthol, cineole, eugenol, citral, citronelle, borneol, linalool, geraniol, evening primrose, camphor, thymol, spirantol, pinene, limonene and terpenoid oils;
j) lipids such as cholesterol, ceramides, sucrose esters and pseudo-ceramides as described in European Patent Specification No. 556 957;
k) vitamins such as vitamin A and E, and vitamin alkyl esters, including vitamin C alkyl esters;
l) sunscreens such as octyl methoxyl cinnamate (Parsol MCX) and butyl methoxy benzoylmethane (Parson 1789)
m) phospholipids;
n) perfume oils; and
o) mixtures of any of the foregoing components.
Particularly preferred hydrophobic benefit agents include esters such as isopropyl palmitate and myristate, and perfume oils.
The hydrophobic benefit agent is preferably present in an amount of from 0.1 to 20 wt %, more preferably 0.5 to 10%, even more preferably 0.5 to 5 wt % by weight of the composition.
The surfactant or surfactants can be selected from any known surfactant suitable for topical application to the human body, provided that they are blended in such a way as to form a stable isotropic system with the hydrophobic components of the composition. Mild surfactants, i.e. surfactants which do not damage the stratum corneum, the outer layer of skin, are particularly preferred. Because of their lathering properties, anionic surfactants are highly preferred components of compositions according to the invention. Where the composition contains an anionic surfactant, it is preferable that the composition also contains a co-surfactant, which can be a nonionic, cationic amphoteric or zwitterionic surfactant. However, compositions according to the invention are substantially soap free; that is, they contain less than about 1% by weight of soap.
A preferred anionic surfactant is alkyl ether sulphate of formula:
RO(CH2CH2O)nSO3M 
where R is an alkyl group of 8 to 22 carbon atoms, n ranges from 0.5 to 10 especially from 1.5 to 8, and M is a solubilising cation.
Another preferred anionic surfactant is fatty acyl isethionate of formula:
RCO2CH2CH2SO3M 
where R is an alkyl or alkenyl group of 7 to 21 carbon atoms and M is a solubilising cation such as sodium, potassium, ammonium or substituted ammonium. Preferably at least three quarters of the RCO groups have 12 to 18 carbon atoms and may be derived from coconut, palm or a coconut/palm blend.
Other possible anionic surfactants included alkyl glyceryl ether sulphates, alkyl sulphosuccinates, acyl taurates, acyl sarcosinates, alkyl sulphoacetates, alkyl phosphates, alkyl phosphate esters, acyl lactylates, acyl glutamates and mixtures thereof.
Sulphosuccinates may be monoalkyl sulphosuccinates having the formula:
R5O2CCH2CH(SO3M)CO2M; 
and amido-MEA sulphosuccinates of the formula:
R5CONHCH2CH2O2CCH2CH(SO3M)CO2M; wherein R6 ranges from C8-C20 alkyl, preferably C12-C15 alkyl and M is a solubilising cation.
Sarcosinates are generally indicated by the formula: R6CON(CH3)CH2CO2M; wherein R5 ranges from C8-C20 alkyl, preferably C12-C16 alkyl and M is a solubilising cation.
Taurates are generally identified by the formula: R5CONR6CH2CH2SO3M; wherein R5 ranges from C2-C20 alkyl, preferably C12-C15 alkyl, R6 ranges from C1-C4 alkyl, and M is a solubilising cation.
Harsh surfactants such as primary alkane sulphonate or alkyl benzene sulphonate will generally be avoided.
If the surfactant comprises soap, the soap is preferably derived from materials with a C5 to C22 substantially saturated carbon chain and, preferably, is a potassium soap with a C12 to C16 carbon chain.
Suitable nonionic surfactants include alkyl polysaccharides, lactobionamides, ethyleneglycol esters, glycerol monoethers, polyhydroxyamides (glucamide), primary and secondary alcohol ethoxylates, especially the C8-C20 aliphatic alcohols ethoxylated with an average of from 1 to 20 moles of ethylene oxide per mole of alcohol. Other suitable nonionics include oil in water emulsifiers such as PEG-40 hydrogenated castor oil.
Suitable further surfactant materials are zwitterionic detergents which have an alkyl or alkenyl group of 7 to 18 carbon atoms and comply with an overall structural formula: 
where R1 is alkyl or alkenyl of 7 to 18 carbon atoms R2 and R3 are each independently alkyl, hydroxyalkyl or carboxyalkyl of 1 to 3 carbon atoms;
m is 2 to 4;
n is 0 to 1;
x is alkylene of 1 to 3 carbon atoms optionally substituted with hydroxyl; and
Y is xe2x80x94CO2 or xe2x80x94SO3.
Zwitterionic surfactants within the above general formula include simple betaines of formula: 
and amido betaines of formula; 
where m is 2 or 3.
In both formulae R1, R2 and R3 are as defined previously.
R1 may, in particular, be a mixture of C12 and C14 alkyl groups derived from coconut so that at least half, preferably at least three quarters, of the group R1 has 10 to 14 carbon atoms. R2 and R3 are preferably methyl.
A further possibility is a sulphobetaine of formula: 
where m is 2 or 3, or variants of these in which xe2x80x94(CH2)3SO3xe2x88x92 is replaced by 
R1, R2 and R3 in these formulae are as defined previously.
Mixtures of any of the foregoing surfactants may also be used.
The surfactants is preferably present at a level of from 10 to 35 wt %, preferably 12 to 30 wt % of the composition.
An optional component in compositions according to the invention is a cationic polymer, such as for example cationic celluloses.
Cationic cellulose is available from Amerchol Corp. (Edison, N.J., USA) in their Polymer JR (trade mark) and LR (trade mark) series of polymers, as salts of hydroxyethyl cellulose reacted with trimethyl ammonium substituted epoxide, referred to in the industry (CTFA) as Polyquaternium 10. Another type of cationic cellulose includes the polymeric quaternary ammonium salts of hydroxyethyl cellulose reacted with lauryl dimethyl ammonium-substituted epoxide, referred to in the industry (CTFA) as Polyquaternium 24. These materials are available from Amerchol Corp. (Edison, N.J., USA) under the tradename Polymer LM-200.
A particularly suitable type of cationic polysaccharide polymer that can be used is a cationic guar gum derivative, such as guar hydroxypropyltrimonium chloride (Commercially available from Rhone-Poulenc in their JAGUAR trademark series).
Examples are JAGUAR C13S, which has a low degree of substitution of the cationic groups and high viscosity, JAGUAR C15, having a moderate degree of substitution and a low viscosity, JAGUAR C17 (high degree of substitution, high viscosity), JAGUAR C16, which is a hydroxypropylated cationic guar derivative containing a low level of substituent groups as well as cationic quaternary ammonium groups, and JAGUAR 162 which is a high transparency, medium viscosity guar having a low degree of substitution.
Preferably the cationic polymer is selected from cationic cellulose and cationic guar derivatives. Particularly preferred cationic polymers are JAGUAR C13S, JAGUAR C15, JAGUAR C17 and JAGUAR C16 and JAGUAR C162, especially Jaguar C13S.
Cationic polymer if present in compositions according to the invention is present at levels of 0.01-1.2%, more preferably 0.05-1.0%, even more preferably 0.1-0.5% by weight of the composition.
In some embodiments an auxiliary structurant or thickener may be added to the composition. Suitable structurant material include swelling clays, for example laponite; cross-linked polyacrylates such as Carbopol (TM) (polymers available from Goodrich); actylates and copolymers thereof; polyvinylpyrrolidone and copolymers thereof; polyethylene imines; polymeric carboxylates, consisting of and including modified and unmodified starches, unsubstituted guar gums, agars, alginates, xanthan gum, carrageenan, cellulose derivatives, exudate gum, gellan gum, gelatin, pectins and seed gums; gellants; and mixtures thereof.
Preferred thickeners for the composition include fumed silica; alkyl silicone waxes; aluminum silicate; fatty acids and derivatives thereof, in particular, fatty acid monoglyceride polyglycol ethers; polyammonium stearate; hydrotalcites; and mixtures thereof. A particularly preferred thickener is PEG-120 methyl glucose dioleate.
The composition may also comprise a viscosity modifying agent, ie a material which adjusts the viscosity of the composition to be that which is suitable for and preferred by consumers. Suitable materials include ethylene glycols, propylene glycols, salts such as sodium chloride and ammonium sulphate; and sucrose esters.
Further examples of structurants and thickeners are given in the International Cosmetic Ingredient Dictionary, Seventh Edition, 1997, published by CTFA (The Cosmetic, Toiletry and Fragrance Association), incorporated herein by reference.
Compositions of the invention may be formulated as propellant driven and dispensed products for washing the skin, for example, bath or shower gels, hand washing compositions or facial washing liquids, and products for washing the hair, as well as post foaming shaving gels. Shower gels, and also post foaming shaving gels are particularly preferred product forms.
Other typical optional components of such compositions include opacifiers, preferably at 0.2 to 2.0 wt %; preservatives, preferably at 0.2 to 2.0 wt %; pH adjusters, typically at 0.05-2.0 wt %; colourants, preferably at 0.05-2.0 wt %; biological extracts, preferably at 0.05-2.0 wt %; humectants, such as glycerol or sorbitol, preferably at 0.1-10.0 wt %; and perfumes, preferably at 0.5 to 2.0 wt %.
The invention will be further illustrated by reference to the following non-limiting examples.